The present invention relates to an apparatus and method for supplying a process solution, such as resist solution or developing solution to be applied to a semiconductor wafer or an LCD substrate. More particularly, the invention relates to an apparatus and method for supplying a process solution, which are suitable to deaerate the process solution, that is, to remove the dissolved gas from the process solution.
To perform photolithography during the manufacture of a semiconductor device, a process solution such as resist solution or developing solution is applied to a surface of a substrate such as a semiconductor wafer. As the minuteness and the integrated scale of the semiconductor circuit patterns recently become higher, it is demanded that the process solution be applied in highly controlled conditions.
To apply the process solution in highly controlled condition, deaeration of the solution must taken into consideration. The process solution, for example, resist solution, contains dissolved gas such as oxygen, nitrogen, argon, carbon dioxide, and the like. The dissolved gas may turn into bubbles in the resist solution while the solution is flowing through the solution applying tube. In this case, the solution applied to a substrate will form a film having an uneven thickness. Since the solution is applied to the substrate in a small amount of a few milliliters, the bubbles may greatly impair the thickness uniformity of the film, and thus the influence of the bubbles is not regregible.
Further, if the dissolved gas turns into bubbles as the solution flows through the solution applying nozzle, the bubbles will impair the precision of the amount of the solution applying to a substrate. This adversely influences the precision of forming a circuit pattern.
As indicated above, the process solution such as resist solution should be applied in highly controlled conditions to form a semiconductor circuit pattern. It is therefore desired that an apparatus and method be provided that can efficiently remove dissolved gas from a process solution.